Parenteral penicillin is the first-line regimen for treating syphilis. However, allergic reactions and poor drug tolerance still present challenging problems with respect to use of this antibiotic. This study aimed to evaluate the efficacy and safety of ceftriaxone, erythromycin, minocycline, tetracycline, and doxycycline for syphilis treatment, compared with penicillin, to determine which antibiotic could be a better substitute for penicillin. This study included 17 articles, comprising 3 randomized controlled trials (RCTs) and 14 observational studies and involving 4,485 syphilis patients. Estimated risk ratios (RRs) and 95% confidence interval (CIs) were used to compare the serological response rates. At the 6- and 12-month follow-ups, the serological response rates were compared by direct meta-analysis and network meta-analysis (NMA). Based on direct meta-analysis, the serological response rates at the 3- and 24-month follow-ups were compared. Our NMA showed a higher serological response rate for ceftriaxone than for penicillin at the 6-month follow-up (RR of 1.12, 95% CI of 1.02 to 1.23). Ceftriaxone was equally effective as penicillin for syphilis in terms of serological response rates, and it was a better substitute for penicillin than ceftriaxone, erythromycin, minocycline, tetracycline, or doxycycline. However, more large-scale, high-quality, double-blind trials are still needed to determine whether ceftriaxone can safely replace penicillin for the treatment of syphilis when necessary. IMPORTANCE Parenteral penicillin is the first-line regimen for syphilis treatment. However, allergic reactions and poor drug tolerance still present emerging threatening problems with respect to use of this antibiotic. Our results showed a higher serological response rate for ceftriaxone than for penicillin at the 6-month follow-up. Sufficient data are not available for demonstrating significant differences in the efficacy of the other four antibiotics (erythromycin, minocycline, tetracycline, and doxycycline) for treating syphilis. In the clinical treatment of syphilis in patients who are allergic to penicillin or for whom penicillin is not available, ceftriaxone appears to be a better alternative treatment. This meta-analysis provides a reference for clinical treatment of syphilis. Currently, a lack of sufficient evidence to guide antibiotic treatment of syphilis exists, and a need for more high-quality RCTs is still present. This network meta-analysis can lay a foundation for further research.

Lyme disease (LD) is a heavy public health burden. The most common manifestations of LD include erythema migrans (EM), Lyme neuroborreliosis (LNB), and Lyme arthritis (LA). The efficacy and safety of antibiotics for treating LD is still controversial. Thus, we performed a network meta-analysis (NMA) to obtain more data and tried to solve this problem. We searched studies in the databases of Embase and PubMed from the date of their establishments until 22 April 2021. Odds ratios (ORs) were used to assess dichotomous outcomes. A total of 31 randomized controlled trials (RCTs) involving 2,748 patients and 11 antibiotics were included. Oral amoxicillin (1.5 g/day), oral azithromycin (0.5 g/day), injectable ceftriaxone, and injectable cefotaxime were effective for treating LD (range of ORs, 1.02 to 1,610.43). Cefuroxime and penicillin were safe for treating LD (range of ORs, 0.027 to 0.98). Amoxicillin was effective for treating EM (range of ORs, 1.18 to 25.66). Based on the results, we thought oral amoxicillin (1.5 g/day), oral azithromycin (0.5 g/day), injectable ceftriaxone, and injectable cefotaxime were effective for treating LD. Cefuroxime and penicillin were safe for treating LD. Amoxicillin was effective for treating EM. We did not observe evidence proving the advantage of doxycycline in efficacy and safety for treating LD, LA, LNB, and EM of children or adults. We did not have sufficient data to prove the significant difference of efficacy for treating LA and LNB in adults and LD in children, the significant difference of safety of oral drugs for treating LD, and the significant difference of safety of drugs for treating EM. IMPORTANCE Some previous studies investigated the efficacy and safety of antibiotics for treating Lyme disease (LD). However, due to technical limitations, several questions regarding the routes of drug administration and the dosages of drug are still unclear, which might be causing problems for clinicians. Hence, we performed network meta-analysis (NMA) to quantitatively analyze the clinical data published during the last 40 years. Here, we demonstrate the evidence regarding the efficacy and safety of antibiotics commonly used for treating LD in adults and children. We found that amoxicillin, azithromycin, ceftriaxone, and cefotaxime were effective for treating LD, but we did not observe significant efficacy and safety of doxycycline for treating LD.